#102 Lecture 2.docx

Anatomy, how to do an image, what you will see on the image, and how to interpret the image for exams. Body Habitus is useful to determine the size, shape, position, and movement of the internal organs. Thoracic Cavity The thoracic cavity begins at the superior thoracic aperture and extends to th...

Anatomy, how to do an image, what you will see on the image, and how to interpret the image for exams. Body Habitus is useful to determine the size, shape, position, and movement of the internal organs. Thoracic Cavity The thoracic cavity begins at the superior thoracic aperture and extends to the inferior thoracic aperture. Thoracic viscera (organs) are in the thoracic cavity. The diaphragm separates the thoracic cavity from the abdominal cavity. The thoracic cavity contains the lungs, heart, organs of the respiratory, cardiovascular, and lymphatic systems, inferior portions of the esophagus, and the thymus gland. Within the cavity are three separate chambers; a single pericardial cavity, right pleural cavities, and left pleural cavities. These cavities are lined by shiny, slippery, and delicate serous membranes. The mediastinum is the potential space in the central area of the thorax behind the sternum. It contains all of the organs of the thoracic cavity except the lungs, like the esophagus, heart, trachea, and great vessels. Respiratory System The trachea is a fibrous tube that is composed of 16-20 C-shaped rings that wrap around the front part of the trachea and the back is flat. Make it rigid. Made up of cartilage that protects the trachea. It is approximately 3 quarters of an inch in diameter and 4.5 inches long. The trachea measures approximately ½ inch in diameter and 4.5 inches in length. The trachea begins in the neck at about the level of the C6 and extends to about the level of T4 or T5. The landmark for T4 or T5 is the sternal notch. The trachea divides into the right or left main bronchi. The trachea follows the midline of the body and in front of the esophagus. The last tracheal cartilage is elongated and has a hook-like process the carina which extends posteriorly on its inferior surface.. The carina is where the trachea divides or bifurcates into two lesser tubes- the primary bronchi. The primary bronchi slant obliquely inferiorly to their entrance into the lungs where they branch out to form the right and left bronchial branches. 1. 2. 3. Alveoli The terminal bronchioles communicate with alveolar ducts. Each alveolar duct ends in several alveolar sacs. The walls of the alveolar sacs are lined with alveoli. Oxygen and carbon dioxide are exchanged by diffusion within the walls of the alveoli.  Lungs Lungs are the organs of respiration. Lungs are made up of a light, spongy, highly elastic substance made of parenchyma and they are covered by a layer of serous membrane. Lungs take up all of the space in the thoracic cage that is not occupied by the thoracic structure. Each lung presents a rounded apex that reaches above the level of the clavicles into the root of the neck and a broad base that rests on the obliquely placed diaphragm which reaches lower in the back and at the sides than in front. The base of the lungs is lower in the back than in the front. Lungs are lower at the sides. The sides of the lungs when inhaled reach into the Medial view of the right lung as seen is the hilum where bronchi and vessels enter into the lungs. Concave to make room for the heart and aorta. The right lung has 2 fissures that divide into 3 lobes. The left lung only has a horizontal fissure which divides it into 2 lobes. The lateral surface of each lung is concave, fitting over the diaphragm and the lateral margins are thin. During respiration, the lungs move inferiorly for inspiration and superiorly for expiration. During inspiration, the lateral margins descend into the deep recess of the parietal pleura called costophrenic angle. The mediastinal surface is concave with a depression called the hilum which accommodates the bronchi, pulmonary blood vessels, lymph vessels, and nerves. The inferior mediastinal surface of the left lung contains a concavity called the cardiac notch which conforms to the shape of the heart. Each lung is double-enclosed in a double, walled serous membrane sac known as a pleura. The inner layer of the pleural sac is called Pulmonary or visceral pleura which closely adheres to the surface of the lung, extends into the interlobar fissures, and is contiguous with the outer layer at the hilum. The parietal pleura is the outer layer that lines the thoracic cavity wall occupied by the lung and closely adheres to the upper surface of the diaphragm. The pleural cavity is the space between the two pleural walls. Fluid might be acculturated between the two layers. Plurasese patients feel the lining rubbing. Each lung is divided into lobes by deep fissures. The fissures lie in an oblique plane inferiorly and anteriorly above so that the lobes overlap each other in the AP direction. Oblique fissures divide the lungs into superior and inferior lobes. The superior lobe lies above and is anterior to the inferior lobes The right superior lobe is divided further by a horizontal fissure creating a right middle lobe. The left lung has no horizontal fissure and no middle lobe. Portion of the left lobe that corresponds in position to the right middle lobe is lingula which is a tongue-shaped process on the anteromedial border of the left lung. This fills the space between the chest wall and the heart. Each five lobes divides into bronchopulmonary segments and is subdivided into smaller units called primary lobules. The primary lobules are the anatomic unit of structure and consist of a terminal bronchiole with its expanded alveolar duct and alveolar sac. Thorax moves forward and up. The base of the lungs meets in the corner recesses. RAO is the best projection of the esophagus when a patient consumes barium contrast. Thymus gland in the lower part of the neck extends into the chest.  A\) Movement of lungs during inspiration and expiration. (B) Costophrenic angles shown *(arrows)* on PA projection of chest. Pharynx The pharynx serves as a passage for air and food and is common to the respiratory and digestive systems. The pharynx is a musculomembranous, tubular structure situated in front of the vertebra and behind the nose, mouth, and larynx. About 5 inches in length and extends from the undersurface of the body of the sphenoid bone and the basilar part of the occipital bone inferiorly to the level of the disk between the sixth and seventh cervical vertebrae where it becomes the esophagus. The nasopharynx lies posteriorly above the soft and hard palates. Upper part of the hard palate from the floor of the nasopharynx. Anteriolythe nasopharynx communicates with the posterior apertures of the nose. The uvula is the hanging posterior aspect of the soft palate and is a small conical process. The oropharynx is the portion extending from the soft palate to the level of the hyoid bone. The laryngeal pharynx lies posterior to the larynx, its anterior wall is formed by the posterior surface of the larynx. This extends inferiorly and is continuous with the esophagus. Larynx Larynx-Organ of voice. Larynx is a movable, tubular structure that is broader above than below and is approximately 1.5 inches in length. Situated below the root of the tongue and in front of the laryngeal pharynx, the larynx is suspended from the hyoid bone and extends from the level of the superior margin of teh fourth cervical vertebra to its junction with the trachea at teh level of the inferior margin of teh sixth cervical vertebra. Epiglottis is situated behind the root of the tongue and the hyoid bone and above the laryngeal entrance. Thyroid cartilage forms the laryngeal prominence or Adam's apple. Piriform recess is located on each side of the larynx and external to its orifice. They are shown as triangular areas on frontal projections when insufflated with air (Valsalva maneuver) or when filled with an opaque medium. Laryngeal cavity is subdivided into three compartments by two pairs of mucosal folds that extend anteroposteriorly from its lateral walls. Superior pairs of folds are the vestibular folds or false vocal cords. Lower two folds are separated from each other by a median fissure called the rima glotidis also called vocal cords. Collectively these are called the glottis. Mediastinum The mediastinum is the area of the thorax bounded by the sternum anteriorly, the spine posteriorly, and the lungs laterally. Esophagus is part of the digestive canal that connects the pharynx with the stomach. Narrow musculomembrouos tube approximately 9 inches. Esophasgus descends through the posterior part of the mediastinum and runs anteriorly to pass through the esophageal hiatus of the diaphragm. The esophagus lies in front of the vertebral column with its anterior surface in close relation to the trachea, aortic arch, and heart. When the esophagus is filled with barium sulfate the posterior border of the heart and the aorta are outlined well in lateral and oblique projections. Frontal, oblique, and lateral images are often used in exams. The Thymus gland is the primary control of the lymphatic system. It is responsible for producing the hormone thymosin which assists in the development and maturation of the immune system. The thymus consists of two pyramid-shaped lobes that lie in the lower neck and superior mediastinum anterior to the trachea and great vessels of the heart and posterior to the manubrium. The thymus reaches its maximum size at puberty and then gradually undergoes atrophy until it almost disappears. Mediastinum contains Heart Great vessels Trachea Esophagus Thymus Lymphatics Nerves Fibrous Tissue Fat Chest x-ray General positioning considerations for the chest The patient is placed in an upright postion whenever possible to prevent engorment of the pulmonary vessels and to allow gravity to depress the diaphragm. Upright positions shows air adn fluid levels. In recumbent position it compresses the thoracic viscera which prevents full expansion of the lungs. The left lateral chest position is most commonly used because it places the heart closer to the IR, resulting in a less magnified heart image. Slight amount of rotation form the PA or lateral projection causes considerable distortion of the heart shadow. PA Criteria =========== Instruct the patient to sit or stand upright. If standing, the weight of the body must be equally distributed on the feet. Position the patient\'s head upright facing forward. Have the patient depress the shoulders and hold them in contact with the grid device to carry the clavicles below the lung apices. In the presence of upper thoracic scoliosis, a faulty body position can be detected by the asymmetric appearance of the sternoclavicular joints. Lateral Criteria ================ Place the side of interest against the IR Have the patient stand so the weight is equally distributed on the feet. The patient should not lean toward or away from the IR holder. Raised the patient\'s arms to prevent the soft tissue of the arms from superimposing the lung fields Instruct the patient to face straight ahead and raise the chin To determine rotation, examine the posterior aspects of the ribs. Radiographs without rotation show superimposed posterior ribs. Breathing Instructions ====================== Normal respirations- the costal muscles pull the anterior ribs superiorly and laterally, the shoulder rises and the thorax expands from front to back and side to side. These changes in the height and AP dimension of the thorax must be considered when the patient is positioned. Deep inspiration causes the diaphragm to move inferiorly resulting in the elongation of the heart. Radiographs of the heart should be obtained at the end of normal inspiration to prevent distortion. More air is inhaled after the second breath and without strain than during the first breath. Pneumothorax is gas or air in the pleural cavity and when suspected one exposure is often made at the end of full inspiration and another at the end of full expiration, to show a small amount of free air in the pleural cavity that might be obscured on the inspiration exposure. Inspiration and expiration radiographs are used to show the movement of the diaphragm, the presence of the foreign boy, and atelectasis (absence of air). Technical Procedure =================== Exposure factors and accessories used in examining the thoracic viscera depend on the radiographic characteristics of the individual patient\'s pathologic condition. Normally chest radiography uses a high kilovoltage peak (kVp) to penetrate and show all thoracic anatomy on the radiograph. The kVp can be lowered if exposures are made without a grid. Appropriate kVp will penetrate the mediastinulm to show a faint image of the spine as well as demonstrate the pulmonary vascular markings o teh lung perpheyr. When possible an SID of 72 inches (183 cm) should be used to minimize magnification of the heart and to obtain a greater spatial resolution of the delicate lung structure. The use of a grid is recommended for opaque areas within the lung fields and to show lung structure through thickened pleural membranes. This technique allows penetration of these opaque areas while maintaining appropriate contrast resolution Radiation Protection ==================== Shield gonads protect patients from unnecessary radiation by restricting the radiation beam using proper collimation. This may be necessary to decrease patient or caregiver anxiety about radiation exposure and when the clinical objectives of the exam are not compromised. PA Projection ============= Properly prepare patients. Have the patient remove everything from the waist up including bras for females. ensure that female patients are not pregnant Any body piercing in the area has to come off. If they have long hair visible towards their back it has to be put up. The jewelry around their neck has to be removed. Do not want any writing on a t-shirt. The routine chest has the patient standing erect because we need to see air-fluid levels. Fluid goes down, air goes up. Alternately sitting erect. Image receptor + Grid --------------------- Use a 14 by 17 inch for each image used on an adult. SID --- Use 72-inch SID to minimize magnification to ensure the heart does not appear magnified. Explain the procedure to the patient and the patient would be wearing a gown with an opening in the back. Ensure gonadal shielding. Two routine projections for the chest are PA and left lateral unless the physician requests for a right lateral. Position of Patient ------------------- If possible always examine patients in an upright position, either standing or seated so that the diaphragm is at its lowest position and air or fluid levels are sen. Engorgement of the pulmonary vessels is also avoided. Patients on a stretcher can be radiographed sitting with their legs dangling over the side of the stretcher if conditions allow. Position of Part ---------------- 1. 2. 3. 4. 5. 6. 7. 8.  9. 10. Central Ray ----------- Central Ray is positioned so it is perpendicular to T7 (inferior angle of the scapula). Point straight at it. Have the patient move their arm and feel the inferior angle of the scapula.Have the patient rotate their shoulders forward until the shoulders hit the IR to move the scapula to the side so you can see the lungs. Have the patient move their arm and feel the inferior angle of the scapula. Collimation ----------- Adjust the radiation field to 17 inches (43 cm) lengthwise and 1 inch (2.5 cm) beyond the lateral shadows but no more than 14 inches (35 cm). The opposite dimensions are used for a crosswise IR. The vertical dimension may be less for smaller patients. Place the side marker in the collimated exposure field. Structures Shown ---------------- PA projection of the thoracic viscera shows the air-filled trachea, the lungs, the diaphragmatic domes, the heart and aortic arch, and if enlarged laterally, the thyroid or thymus gland. The vascular marks are much more prominent on the projection made at the end of expiration. \(A) PA chest in a man. (B) PA chest showing pneumoconiosis in both lungs (multiple, irregularly shaped white areas show built-up coal dust). PA chest IR is in the wall bucky or using a digital image receptor. Cassettes should be lengthwise on most patients. If the patient is hyperstentic then turn crosswise. Some patients if they are not hyperstentic have to be crosswise. The midsagittal plane is not perpendicular to the IR, so we get a rotation of the chest. The end on the left side is further away from the spine than the other side. The one on the right side is away from the spine and the left side is close, this needs to be repeated. Evaluation Criteria ------------------- The following should be clearly seen: 1. 2. 3. a. b. c. 4. 5. 6. 7. 8. 9. Lateral Projection ================== Right or Left Postion ### Image Receptor + Grid CR Plate is 14 by 17 inches (35 by 43 cm) lengthwise ### SID A minimum of 72 inches (183 cm) is recommended to decrease the magnification of the heart and increase the spatial resolution of the thoracic structures. ### Position of the Patient 1. 2. 3. 4. Lateral chest projection (side closest to the IR) most of the time for the left lateral because it places the heart closer to the IR. ### Position of Part 1. 2. 3. 4. 5. 6. 7. 8.  ### Central Ray 1. ### Collimation 1. ### Structures Shown Left lateral position would show the heart, aorta, and left-sided pulmonary lesions. The right lateral position would show the right-sided pulmonary lesions. These lateral positions are used extensively to show the interlobar fissures, to differentiate the lobes, and to localize pulmonary lesions. ### Evaluation Criteria The following should be clearly seen: 1. 2. 3. 4. a. b. c. d. 5. Foreshortening Forward bending 6. 7. 8. End at lateral chests for quiz on Monday.